1. Field of the Invention
The invention concerns in-line roller skates including a chassis on which a shoe is mounted.
2. Description of Related Art
Roller skates can be classified into two main families, namely,
skates in which the rollers or wheels are disposed on axles, generally two axles, one behind the other, and PA1 skates in which the rollers or wheels are mounted individually in-line one behind the other, this type of skate often being called an "in-line skate".
In-line skates often have three or more wheels the respective rotation axes of which are at different heights so that only the wheel or wheels under the middle of the foot are in contact with the ground when the skater's foot is parallel to the ground.
The wheels at the ends of the skate then have a diameter and/or are mounted in such a manner that they come into contact with the ground only when the skate is inclined towards the front or towards the rear, which makes the skate manoeuvrable and enables easy and fast changes of direction.
However, this arrangement of the wheels makes the skate less stable so it does not readily keep to the required trajectory, in particular in curves.
In a curve the skate is inclined laterally and also tends to pivot relative to the bearing point of the wheel that is in contact with the ground. Accordingly, at least with three in-line wheels, it is as if the skate is in contact with the ground at a single point, giving it three degrees of freedom in rotation. These skates are therefore intended for very experienced skaters wanting to perform particular figures.
For ordinary use by inexperienced skaters, skates in which all the wheels touch the ground at the same time are preferable, because they have the advantage of being unconditionally stable.
This being so, they have the drawback of not maintaining simultaneous contact of all the wheels with irregular ground and of making contact with the ground more brutal and therefore less comfortable when executing figures.
To overcome this drawback, document WO 96/26 775 teaches the provision of an in-line roller skate having a chassis mounted under the sole of a shoe and two bogies in each of which two wheels are mounted rotatably and in-line, the bogies themselves pivoting about an axis transverse to the alignment of the wheels. The bogies are spring-loaded into a position in which all the wheels are at the same height. Although this arrangement offers the skater some comfort, it can also cause a nose dive or jamming of the front of the skate if the latter has to pass over a discontinuity in the ground on its path. Especially if the discontinuity is sudden, the front wheel then strikes it or is stopped by it, tilting the skate towards the front. Moreover, on starting off, when the skater generally "pushes" backward with the toes, raising the heel, the front bogie will remain in contact with the ground and tend to shoot out towards the rear.
The aim of the present invention is to remedy the disadvantages of prior art roller skates.